a. Field of the Invention
The present disclosure relates generally to a fault detection and abatement system, and more particularly to a system and method of automatic detection and prevention of motor runaway.
b. Background Art
Electrophysiology (EP) catheters are used in a variety of diagnostic and/or therapeutic medical procedures to correct conditions such as atrial arrhythmia, including for example, ectopic atrial tachycardia, atrial fibrillation, and atrial flutter. Arrhythmia can create a variety of dangerous conditions including irregular heart rates, loss of synchronous atrioventricular contractions and stasis of blood flow which can lead to a variety of ailments.
In a typical EP procedure, a physician manipulates a catheter through a patient's vasculature to, for example, a patient's heart. The catheter typically carries one or more electrodes that may be used for mapping, ablation, diagnosis, and the like. Once at the target tissue site, the physician commences diagnostic and/or therapeutic procedures, for example, ablative procedures such as radio frequency (RF), microwave, cryogenic, laser, chemical, acoustic/ultrasound or high-intensity focused ultrasound (HIFU) ablation, to name a few different sources of ablation energy. The resulting lesion, if properly located and sufficiently contiguous with other lesions, disrupts undesirable electrical pathways and thereby limits or prevents stray electrical signals that can lead to arrhythmias. Such procedures require precise control of the catheter during navigation to and delivery of therapy to the target tissue site, which can invariably be a function of a user's skill level.
Robotic catheter systems are known to facilitate such precise control. Robotic catheter systems generally carry out (as a mechanical surrogate) input commands of a clinician or other end-user to deploy, navigate and manipulate a catheter and/or an introducer or sheath for a catheter or other elongate medical instrument, for example, a robotic catheter system described, depicted, and/or claimed in U.S. application Ser. No. 12/347,811 entitled “ROBOTIC CATHETER SYSTEM” owned by the common assignee of the present disclosure and hereby incorporated by reference in its entirety. Such robotic catheter systems include a variety of actuation mechanisms, such as electric motors, for controlling translation and deflection of the catheter and associated sheath. A malfunction in one or more of the motors (e.g., a runaway condition) may result in an unexpected and/or undesirable movement or stoppage of movement of the catheter or sheath.
Motor runaway (i.e., a motor fault condition) may manifest itself with the motor moving in the “wrong” direction (i.e., moving away from its current position in a direction opposite that needed to reach the prescribed target position). In addition, the motor may overshoot the prescribed target position, even though going in the correct direction. There are many reasons that these and other fault conditions can occur, including, for example, motor “over current”, noise issues, motor firmware anomalies as well as owing to the mechanical characteristics of the motors themselves. While knowing the root cause of these fault conditions may be useful in overall system design (e.g., to avoid the occurrence of the faults in the first place), there nonetheless remains a need to detect and abate such fault conditions when they occur.
There is therefore a need for a system and method that minimizes or eliminates one or more problems as set forth above.